Evaluating the Human Likeness of an Android by Comparing
Gaze Behaviors Elicited by the Android and a Person
Takashi Minato1 ,Michihiro Shimada1 ,Shoji Itakura2 4 ,Kang Lee3 ,and Hiroshi Ishiguro1 4
1

Department of Adaptive Machine Systems, Graduate School of Engineering, Osaka University
2-1 Yamada-oka, Suita, Osaka 565-0871, Japan2

Department of Psychology, Graduate School of Letters, Kyoto University
Yoshida Honmachi, Sakyo-ku, Kyoto 606-8501, Japan3

Department of Psychology, University of California, San Diego
9500 Gilman Drive La Jolla, CA 92093-0109, U.S.A.
4Intelligent Robotics and Communication Laboratories,

Advanced Telecommunications Research Institute International
2-2-2 Hikaridai, Keihanna Science City, Kyoto 619-0288, Japan
minato@ams.eng.osaka-u.ac.jp

Abstract
Our research goal is to discover the principles underlying natural communication among individuals and to establish a methodology for the development of expressive humanoid robots. For
this purpose we have developed androids that closely resemble human beings. The androids enable
us to investigate a number of phenomena related to human interaction that could not otherwise
be investigated with mechanical-looking robots. This is because more humanlike devices are in abetter position to elicit the kinds of responses that people direct toward each other. Moreover, wecannot ignore the role of appearance in giving us a subjective impression of human presence or intelligence. However, this impression is influenced by behavior and the complex relationship between
appearance and behavior. This paper proposes a hypothesis about how appearance and behavior are
related, and maps out a plan for android research to investigate this hypothesis. We then examine
a study that evaluates the human likeness of androids according to the gaze behavior they elicit.
Studies such as these, which integrate the development of androids with the investigation of humanbehavior, constitute a new research area that fuses engineering and science.

keywords: android, human-robot communication, human likeness, appearance and behavior, gaze behavior

11

Introduction

Our everyday impressions of intelligence are subjective phenomena that arise from our interactions withothers. The development of systems that support rich, multimodal interactions will be of enormous value.
Our research goal is to discover the principles underlying natural communication among individuals andto establish a methodology for the development of expressive humanoid robots. The top-down designof robots that support natural communication is impossible because human models do not fulfill thenecessary requirements. We adopt a constructivist approach that entails repeatedly developing andintegrating behavioral models, implementing them in humanoid robots, analyzing their flaws, and thenimproving and reimplementing them [1].
By following this constructivist approach in a bottom-up fashion, we have developed a humanoid
robot “Robovie,” which has numerous situation-dependent behavior modules and episode rules to govern
the various combinations of these modules and rules [2]. This has enabled us to study how Robovie’s
behavior influences human-robot communication [3]. However, based on the fact that human beings
have evolved specialized neural centers for the detection of bodys and faces (e.g., [4]), we can inferthat a humanlike appearance is also important. Apart from gestures, human beings may also possessmany biomechanical structures that support interaction, including scores of muscles for controlling facial
expressions and the vocal tract. Robovie’s machinelike appearance will have an impact on interaction,
thereby preventing us from isolating the effects of behavior. Other studies have also tended to focus
only on behavior, and have entrusted the robot’s appearance to an artistic designer. However, in order
to isolate the effects of behavior from those of appearance, it is necessary to develop an android robotthat physically resembles a person. Our study addresses the appearance and behavior problem from thestandpoint of both engineering and science. We also explore the essence of communication through thedevelopment of androids.
Studies on androids have two research aspects:• The development of a humanlike robot based on mechanical and electrical engineering, robotics,
control theory, pattern recognition, and artificial intelligence.
• An analysis of human activity based on the cognitive and social sciences.
These aspects interact closely with each other: in order to make the android humanlike, we must
investigate human activity from the standpoint of the cognitive and behavioral sciences as well as theneurosciences, and in order to evaluate human activity, we need to implement processes that support itin the android.
Research on the development of communication robots has benefited from insights drawn from thesocial and life sciences. However, the contribution of robotics to these fields has thus far been insufficient
partly because conventional humanoid robots appear mechanical and, therefore, have an impaired ability
to elicit interpersonal responses. To provide an adequate testbed for evaluating models of humaninteraction, we require robots that allow us to consider the effects of behavior separately from those of2

Healthy human

Familiarity

Uncanny valley

Toy robot

Similarity to human
CorpseFigure 1: The uncanny valley [5, 6].

appearance.
Conversely, research in the social and life sciences generally takes a humanlike appearance for granted
or overlooks the issue of appearance altogether. Thus, the applicability of such research is unclear. However, these problems can be potentially overcome through the judicious use of androids in experimentswith human subjects. The application of androids to the study of human behavior can be viewed as a
new research area that fuses engineering and science, in contrast with existing approaches in humanoid
robotics that fail to control for appearance. This paper proposes a direction for android research basedon our hypothesis on the relationship between appearance and behavior. It also reports a study that
evaluates the human likeness of an android based on human gaze behavior.
Gaze behavior in human-human interaction has been studied in psychology and cognitive science.
For example, some psychological researchers studied functions of eye contact in human-human conversation [7] and a relationship between duration of eye contact and interpersonal relationship [8]. According
to existing studies on human gaze behavior, we can infer that the gaze behavior is influenced by interpersonal relationship. Conversely, we can infer that the interpersonal relationship can be evaluated byobserving the person’s gaze behaviors. In this paper, gaze behaviors in human-android interaction arecompared with those in huamn-human interaction in order to evaluate human likeness of an android.

2

A Research Map based on the Appearance and Behavior Hypothesis

2.1

A Hypothesis about a Robot’s Appearance and Behavior

It may appear that the final goal of android development should be to realize a device whose appearance
and behavior cannot be distinguished from those of a human being. However, since there will always
be subcognitive tests that can be used to detect subtle differences between the internal architecture ofa human being and that of an android [9, 10], an alternative goal could be to realize a device that is3

uncanny valley with respect toappearance and behavior
Evaluation ofinteraction

Human

Evaluation ofinteraction

uncanny valley
Si

Generation of natural motionmuncanny valley

y
rit
ila
or
vi
ha
be
of

Simil

e
aranc
f appearity oHumansynergistic effect ofappearance and behavior
Evaluation ofinteractionsynergy hill

Synthesizing

synergy hill

Human

Si

m

ila
rit
y

of

be
ha
vi

or

Human

Si
m
y
rit
ila
or
vi
ha
be
of

Simil

arity

ce
earan
of appuncanny valley

Design of methods
for evaluating interactionri
Similace Development of humanlike robots
pearanty of ap

Figure 2: The extended uncanny valley and a map for its investigation.

almost indistinguishable from human beings in everyday situations. In the process of pursuing this goal,
our research also aims to investigate the principles underlying interpersonal communication.
A significant problem for android development is the “uncanny valley,” which was first suggested
by Mori [5, 6]. He discussed the relationship between a robot’s similarity to a human and a subject’s
perception of familiarity. A robot’s familiarity increases with its similarity until a certain point isreached at which imperfections cause the robot to appear repulsive (Fig. 1). This sudden drop is termed
as the uncanny valley. A robot in the uncanny valley may seem like a corpse. We are concerned thatthese robots we create in our development of androids could also fall into the uncanny valley owing toimperfections in appearance. Therefore, it is necessary to adopt a methodology that will enable us toovercome the uncanny valley.
In the figure, the effect of similarity can be decomposed into the effects of appearance and behavior because both factors interdependently influence human-robot interaction. We hypothesize that therelationship between appearance and behavior can be characterized by the graph in Fig. 2. Figure 2 superimposes graphs derived from the uncanny valley hypothesis with respect to appearance and behavior
as well as the hypothesis that there is a synergistic effect on interaction when appearance and behavior
are well matched [11]. Simply put, we hypothesize that an android’s uncanniness can be mitigated byits behavior, if the behavior closely resembles that of a person.

2.2

The Android Research Map

The axes in Fig. 2 are not clearly defined. How do we quantify similarity and how do we evaluate
human-robot interaction? In order to answer these questions, three main research issues need to beaddressed.

4

Figure 3: The developed android Repliee R1.

A method to evaluate human-robot interaction Human-robot interaction can be evaluated byits degree of “naturalness.” Therefore, it is necessary to compare human-human and human-robot
interactions. There are qualitative approaches to measure a mental state using methods such as thesemantic differential (SD) method. There also exist quantitative methods to observe an individual’s
largely unconscious behavior, such as gaze behavior, interpersonal distance, and vocal pitch. Theseobservable responses reflect cognitive processes that we might not be able to infer from responses to aquestionnaire. In this research, we study how a human subject’s responses reflect the humanlike qualityof an interaction and how these responses are related to the subject’s mental state.
Implementing natural motion in androids

In order to elucidate the types of motion that makepeople perceive an android’s behavior as being natural, we attempt to mimic an individual’s motion
precisely and then monitor how a human subject’s interaction with the android degrades as we remove
some aspect of the android’s motion. A straightforward method by which to animate the android
is through the implementation of the motion of an actual human subject, as measured by a motion
capture system. Most methods that use a motion capture system assume that a human body has
the same kinematic structure as a robot and calculate the joint angles using the robot’s kinematics(e.g., [12]). However, since the kinematic structure of humans and robots differ, there is no guaranteethat the robot’s motion, as generated from the angles, will resemble human motion. Therefore, we
require a method that will ensure that the motions we view at the surface of the robot resemble thoseof a human being [13].
The development of humanlike robots

We have developed two androids that are currently being

used for experimentation. Repliee R1, shown in Fig. 3, is based on an actual five-year-old girl. We
took a cast of her body to mold the android’s skin, which is composed of a type of silicone that has ahumanlike feel. The silicone skin covers the entire body of the android. To enable it to assume various
postures, it has nine degrees of freedom in the head (two for the eyelids, three for the eyes, one for the5(a) Repliee Q1(b) Repliee Q2

Figure 4: The developed androids Repliee Q1 and Repliee Q2. The details of the inside mechanism areblurred.

mouth, and three for the neck) and many free joints. All actuators (electrical motors) are embedded
within the body. The main limitations of this android are as follows:• Repliee R1’s range of motion is limited by the low elasticity of the silicone skin.
• The facial expression cannot be changed.
• The eye and eyelid mechanisms are not perfectly realized, which is a drawback because people areusually sensitive to imperfections in the eyes.
These limitations must be overcome in order to achieve a humanlike appearance.
Repliee Q1, shown in Fig. 4 (a), is our other android; this android was developed to realize humanlike
motion. It has 31 degrees of freedom in the upper body. It can generate various kinds of micro-motions
such as the shoulder movements that are typically caused by human breathing. Silicone skin covers
only its head, neck, hands, and forearms thereby enabling a wide range of motions to be realized. The
compliance of the air actuators makes for safer interactions. Highly sensitive tactile sensors mounted
just under the android’s skin enable contact interaction.
Repliee Q1 has now been upgraded to Repliee Q2 shown in Fig. 4 (b). It has 42 degrees of freedom
and can make facial expressions and finger motions in addition to the movements that Repliee Q1 canmake. It has 16 degrees of freedom in the head (one for the eyebrows, one for the eyelids, three for theeyes, seven for the mouth, one for the cheeks, and three for the neck). The face was modeled after aparticular Japanese woman in order to realize a more humanlike appearance. The facial expressions of
the android enable various social interactions.
We are studying the appearance and behavior problem while integrating these research issues. In thenext section, we present a study to evaluate the human likeness of the android based on human gaze6behavior during communication.

3

Evaluation of the Human Likeness of the Android

In order to make the android humanlike, we must evaluate the human likness of the android. Therefore,
as mentioned above, it is necessary to compare human-human and human-android interactions. Apartfrom the android, Oztop et al. [14] adopted an experimental paradigm of motor interference to investigate
how similar the implicit perception of a humanoid robot is to a human agent. They measured the amountof interference in a subject’s movement when s/he performed an action which was incongruent to other’s
action, and evaluated the human likeness of the humanoid robot with the interference effect. In theevaluation of a human-robot interaction, methods of evaluating a human subject’s (largely unconscious)
responses provide a complementary source of information to the insights gleaned from a questionnaireor focus group. Therefore, the difference between human-human and human-android interactions canbe evaluated by observing such person’s responses as can be influenced by a social relationship to otherindividuals.
In our previous work, we studied the interaction between the android Repliee R1 and a person [15].
We focused on the subject’s gaze fixation during a conversation. The pattern of fixation in the case of
the android interlocutor was different from that of a human interlocutor. Many subjects perceived theandroid’s appearance and movement to be artificial. Thus, we concluded that the unnaturalness of theandroid affected the subjects’ gaze fixation.
This paper evaluates the human likeness of the android Repliee Q1, which has an improved appearance and better movement. The evaluation method in the previous work was not considered appropriate
for use because the task of the subject was not well controlled. In this study, we focus on a particular
aspect of gaze behavior, which is evaluated through a set of experiments. On one hand, this helps toinvestigate the design methodology of humanoid robots; on the other hand, by studying the nature ofgaze behavior, we can contribute to cognitive science and psychology.

3.1

Breaking Eye Contact while Thinking

Gaze behaviors in human-human interaction have been studied in psychology and cognitive science,and the gaze behavior in human-android interaction can be compared to it. Some gaze behaviors areconscious (e.g., people look at one another to coordinate turn-taking [16]) and others are unconscious.
This paper focuses on breaking eye contact while thinking, which is one of unconscious gaze behaviors.
The tendency to break eye contact during a conversation has been studied in psychology. While
thinking, people sometimes break eye contact (avert their eyes from the interlocutor). There are threemain theories that explain this behavior:• The arousal reduction theory
There is a fact that arousal is the highest when a person makes eye contact during face-to-face7

Questioner(Human or Android)

Subject
20deg

Up
Up Right

Up Left

Right

Left

Down Right

20deg

Down Left

Down(a) The experimental setup(b) The discrete eye directions

Figure 5: The experimental scene and the eight averted gaze directions.

communication [17]. This theory suggests that people break eye contact while thinking to reduce
their arousal and concentrate on the problem [18].
• The differential cortical activation hypothesis
This hypothesis suggests that brain activation induced by thinking tasks leads individuals to shift
their gaze away from the central visual field [19].
• The social signal theory
This theory suggests that gaze behavior acts as a social signal; people break eye contact to inform
others that they are thinking.
If breaking eye contact were a kind of social signal, we would expect it to be influenced by theinterlocutor. Psychological researchers have reported that there is experimental evidence to support thesocial signal theory [20, 21]. We report an experiment that compares subjects’ breaking of eye contact
with human and android interlocutors.
We hypothesize that if the manner in which eye contact is broken while thinking acts as a social
signal, subjects will produce different eye movements if the interlocutor is not humanlike or if thesubjects do not consider the interlocutor to be a responsive agent. Conversely, if eye movement does
not change, it supports the contention that subjects are treating the android as if it were a person orat least a social agent.

3.2

Experiment 1

3.2.1

Procedure

The subjects were made to sit opposite a questioner (Fig. 5 (a)). The subjects’ eye movements were
measured while they were thinking about the answers to questions posed by the questioner. There were
two types of questions: know questions and think questions. The know questions were used as a control
condition. Know questions were those to which the subjects already knew the answers (e.g., “How old

8

Up
25

Up

20

20

Up right

Up left
15

Knowquestions

5

Right

Up right

Thinkquestions

10

Left

0

Right

16

Think
questions

8
4

Know
questions0

Down right
Down right

Up left

12

Left

Down left

Down left
Down
Down

(a) Human questioner(b) Android questioner

Figure 6: Average percentage of duration of gaze in eight averted directions (experiment 1) [%].

are you?”). Think questions, on the other hand, were those questions to which the subjects did notalready know the answers because the subject was compelled to derive the answer (e.g., “Please tell mea word that consists of eight letters.”).
The subjects were asked 10 know questions and 10 think questions in random order. Their faces
were videotaped and their gaze direction was coded from the end of the question to the beginning of theanswer. The video records of each subject’s eye movements were analyzed frame by frame. The average
duration of gaze in the eight directions shown in Fig. 5 (b) was then calculated.
Two types of questioners were used: a Japanese person (human questioner) and the android Repliee
Q1 (android questioner). In order to make the android appear as humanlike as possible, we conducted
the experiment of the case of the android questioner in the following manner: A speaker embedded in
the android’s chest produced a prerecorded voice. In order to make the android appear natural, it was
programmed such that it displayed micro-behaviors such as eye and shoulder movements. At first, theexperimenter seated beside the android explained the experiment to the subject in order to habituate
the subject to the android. During the explanation, the android behaved like an autonomous agent (e.g.,
it continuously made slight movements of the eyes, head, and shoulders, while yawning occasionally). It
seemed that the subject actually believed that the android was asking questions autonomously; in reality,
however, the questions were being manually triggered by an experimenter seated behind a partition.
The subjects were Japanese adults (six men and six women between 20 and 23 years of age in thecase of the human questioner, and four men and four women between 21 and 33 years of age in the caseof the android questioner). The subjects to interact with the human questioner were recruited from a
university student population, and the subjects to interact with the android questioner were recruitedfrom a temporary employment agency. Most of them were unfamiliar with the android. Each subject
was asked to read and sign a consent form before the experiment. In order to avoid that a subject was
asked same questions, each subject participated in only one case of questioner.
9

Table 1: Mean and standard deviation of gaze duration in the case of the human questioner (experiment1) [%].

Think

Know

Down right

Down

Down left

Right

Left

Up right

Up

Up left

Mean

5.42

20.0

9.29

11.3

16.2

2.79

2.62

4.96

Std.

6.73

17.3

13.1

11.4

17.3

4.36

4.66

6.37

Mean

5.96

19.0

2.69

8.25

15.2

1.83

0.752

3.05

Std.

6.43

24.8

4.07

14.5

12.8

3.40

1.87

5.76

Table 2: Mean and standard deviation of gaze duration in the case of the android questioner (experiment1) [%].

Think

Know

3.2.2

Down right

Down

Down left

Right

Left

Up right

Up

Up left

Mean

14.1

14.4

7.23

6.87

16.5

8.62

4.42

2.63

Std.

13.8

13.9

4.41

7.89

13.3

14.2

5.93

2.26

Mean

6.53

7.57

7.87

5.10

7.47

3.73

2.29

2.18

Std.

8.26

12.0

9.77

8.47

7.41

8.36

5.73

3.47

ResultTable 1 shows the average percentage of times that the subjects looked in each eye direction in the caseof the human questioner; this has been illustrated by the polar plot in Fig. 6 (a). In the same manner,
Table 2 and Fig. 6 (b) show the results in the case of the android questioner.
In order to examine the effect of questioner on the duration of breaking eye contact, a repeatedmeasures three-way ANOVA with one between subject factor (questioner) and two within subject factors (question type and eye direction) was conducted. There were significant effects of question type(F (1, 18) = 56.8, p < 0.000001), eye direction (F (7, 126) = 4.28, p < 0.0005), and interaction between
questioner and question type (F (1, 18) = 6.41, p < 0.05). No simple main effect of questioner was found.
In order to examine the interaction effect, repeated measures two-way question type × eye direction
ANOVAs were conducted in the case of both questioner. A significant effect of question type was found(F (1, 112) = 5.74, p < 0.05) in the case of the android questioner; however, no significant effect ofquestion type was found in the case of the human questioner.
As can be seen in Fig. 6 (a), in the case of the human questioner, subjects tend to avert their eyes
downward when a question is asked, even if they are not required to derive the answer. Thus, the averted
eye direction does not depend on the question type. It is said that Japanese frequently avoid making
eye contact during conversations [22, 23]. Therefore, it can be owing to Japanese culture that there isno difference between results of both question types in the case of the human questioner. Meanwhile,for the android questioner, the averted eye direction changes depending on the question type, as can beseen in Fig. 6 (b). The subjects looked around more frequently for the think questions as compared to10the know questions. The subjects’ mental state in the case of the android questioner appeared to bedifferent from that in the case of the human questioner. According to our hypothesis, this difference
suggests that the subjects consider the android to be a different kind of agent from a person. Experiment
2 was conducted to obtain evidence to support the above inference.

3.3

Experiment 2

In experiment 2, we prepared another situation that required subjects to think about the answer.
There is a commonsense belief, known as “deceiver stereotype” [24]; people who are deceptive avoid eye
contact. Some researchers have shown that people use speaker’s eye gaze display to detect and inferdeception (e.g., [25]). It can be inferred that people unconsciously avoid eye contact when they deceive
an interlocutor. In the experiment, a questioner posed questions to the subjects, who were told in
advance to answer either truthfully or dishonestly. When the subjects were told to answer dishonestly,
they had to convince the questioner that they were telling the truth (i.e., they had to deceive thequestioner). We measured subjects’ eye movements while they were thinking about the answers. We
hypothesized that the subjects’ gaze behavior would change if they did not treat the android as if itwere a person.
3.3.1

Procedure

We conducted an experiment almost identical to that described in section 3.2.1, except for the factthat in this experiment, the subjects were instructed to answer the questions in a particular manner.
Before being asked a question, the subjects were shown a cue card on which the word true or false
was written by an experimenter seated behind a partition. The questioner could not see the card. If
the card had true written on it (true answer), the subjects were instructed to answer the subsequent
question truthfully. If the card had false written on it (false answer), they were instructed to answer
the subsequent question with a dishonest but convincing answer. The subjects had to answer fivequestions truthfully and five questions while lying convincingly. The questions required subjects toprovide personal information (e.g., “When is your birthday?”); thus, it was impossible for the questioner
to know the truth.
The subjects were Japanese adults (five men and six women between 20 and 23 years of age in thecase of the human questioner, and six men and ten women between 21 and 35 years of age in the caseof the android questioner). The subjects to interact with the human questioner were the same as thoseparticipated in the case of human questioner of experiment 1 (one subject was removed). The subjects
to interact with the android questioner were recruited from a temporary employment agency. Most ofthem were unfamiliar with the android. Each subject was asked to read and sign a consent form before
the experiment. In order to avoid that a subject was asked same questions, each subject participatedin only one case of questioner.

11

Up

Up

20

Up right

15

16

Up left

10

12

Up right

Trueanswers
False
answers

5

Right

Left

Up left

8

False
answers

4
0

Right

True
answers

Left

0

Down right

Down left

Down right

Down left
Down

Down

(a) Human questioner(b) Android questioner

Figure 7: Average percentage of duration of gaze in eight averted directions (experiment 2) [%].

3.3.2

ResultTable 3 shows the average percentage of times that the subjects looked in each eye direction in the caseof the human questioner; this is illustrated by the polar plot in Fig. 7 (a). In the same manner, Table 4
and Fig. 7 (b) show the results in the case of the android questioner.
A repeated measures three-way ANOVA with one between subject factor (questioner) and two within
subject factors (answer type and eye direction) revealed significant effects of questioner (F (1, 25) =7.21, p < 0.05), eye direction (F (7, 175) = 5.64, p < 0.00001), and interaction between answer type andeye direction (F (7, 175) = 2.72, p < 0.05). In order to examine the interaction effect, repeated measures
two-way answer type × eye direction ANOVAs were conducted, and no significant effect of answer type
was found in the case of both questioner.
As in experiment 1, the subjects tend to avert their eyes downward when they are asked a question.
From the result in experiment 1, it is predicted that there is a difference in gaze behavior between
the two answer types; however, there is no significant difference. This may be because the subjects
attempted to show similar reactions in the case of both answer types. Thus, the subjects succeeded inmasking their gaze behavior to deceive the questioner.
As can be seen in Fig. 7 (a) and Fig. 7 (b), contrary to the results obtained in experiment 1, thesubjects looked around in the case of the human questioner more frequently as compared to in thecase of the android questioner. Daibo and Takimoto [26] have reported that subjects’ body motions(e.g., talking and gaze motion) increase when they are required to convince a person of an opinion
that is different from their own. They suggested that subjects experience strain or uneasiness owing totheir deception, and their unintentional behavior becomes more apparent. Our results also suggest that
subjects experienced a strain when answering the human questioner but not in the case of the android
questioner. The subjects might have believed that the android questioner would be unable to detect

12

Table 3: Mean and standard deviation of gaze duration in the case of the human questioner (experiment2) [%].

True

False

Down right

Down

Down left

Right

Left

Up right

Up

Up left

Mean

5.22

16.7

1.12

1.07

15.4

4.04

6.81

4.02

Std.

8.68

18.6

3.36

2.27

13.7

11.4

10.4

6.03

Mean

0.989

16.0

3.60

6.00

5.08

2.25

10.4

15.9

Std.

1.82

20.9

6.74

10.9

7.94

5.65

12.4

23.8

Table 4: Mean and standard deviation of gaze duration in the case of the android questioner (experiment2) [%].

True

Flase

Down right

Down

Down left

Right

Left

Up right

Up

Up left

Mean

2.94

9.94

1.71

6.31

4.59

0.0682

0.941

0.878

Std.

6.63

14.7

6.62

13.3

7.44

0.273

2.58

2.33

Mean

0.249

13.8

3.37

9.45

4.31

0.00

0.450

1.26

Std.

0.859

17.6

5.49

19.3

6.63

0.00

1.23

2.95

their deception. This supports the belief that subjects do not treat the android as if it were a person.

3.4

Summary

In the above experiments, the subjects made unconscious interpersonal responses – they broke eye
contact while thinking – in the case of the android Repliee Q1. This fact suggests that Repliee Q1 ishumanlike. However, the gaze pattern is different from that in the case of the human questioner. Thus,
there still remains an unnaturalness in the communication between the subject and the android.
The difference in gaze behavior with respect to the different questioners suggests that breaking eye
contact while thinking is not only induced by brain activity but also has a social meaning. However,before such evidence can be obtained, it is necessary to compare the gaze behaviors elicited by the
android and a person. Furthermore, it was found that the breaking of eye contact could be a response
in order to evaluate the android’s human likeness. If eye movement in the case of the android questioner
is the same as that in interpersonal communication, it is suggested that subjects treat the android as if
it were a person or at least a social agent. In order to make the results more convincing, it is necessary
to compare these results with those obtained for different questioners, such as more machinelike robots.

4

Conclusion

This paper proposed a hypothesis about how appearance and behavior are related and mapped out aplan for android research in order to investigate the hypothesis. The action of breaking eye contact while13

thinking was considered from the standpoint of the appearance and behavior problem. In the study, weused the android to investigate the sociality of gaze behavior while thinking and obtained evidence thatdiffers from psychological experiments in human studies. Furthermore, it was found that the breaking ofeye contact could be a measure of an android’s human likeness. However, this study is only preliminary,
and a more comprehensive study is required to explain the results in order to contribute to human
psychology.

Acknowledgement
We have developed the android robots, Repliee R1, Repliee Q1, and Repliee Q2, in collaboration with
Kokoro Company, Ltd.

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